1. Field of the Invention
The present invention relates to a vehicular interior member manufacturing method (a method of manufacturing a vehicular interior member) and an airbag rupturing groove manufacturing method (a method of manufacturing an airbag rupturing groove). More particularly, the present invention relates to a method of manufacturing an airbag rupturing groove which forms an airbag rupturing groove in a vehicular interior member having a hard substrate layer and a skin layer, and a method of manufacturing a vehicular interior member which includes a process for forming an airbag rupturing groove.
2. Description of Related Art
Conventionally, a vehicle is equipped with an airbag to decrease an impact for drivers and the like at the time of a collision. A vehicular interior member (hereinafter also simply referred to as ‘an interior member’) such as an instrument panel, a door panel and the like is provided with an airbag rupturing groove having a thin-wall portion in order that the interior member breaks and the airbag reliably inflates by the deployment force of an airbag. Also, when such airbag rupturing groove is formed, the interior member of an invisible type is used, in which the airbag rupturing groove is formed on the back side of the interior member. This is because it does not impair interior decorations of the vehicle, and the airbag rupturing groove is not easily recognized from the front surface side.
Here, if the width of the airbag rupturing groove is broad in forming the airbag rupturing groove on the back side of the interior member as the invisible type, it is possible that invisibility from an exterior surface decreases, owing to expansion and contraction of the skin with the time change. Therefore, there is a method for producing the airbag rupturing groove as narrow as possible by using a knife type cutter, an engraving knife and the like instead of using a heat fusion blade or an ultrasonic cutter.
Further, since whether not an interior member reliably deploys at the airbag deployment (collision) has great influence on the drivers' safety, it is requested that the remaining thickness of the skin layer after having formed the airbag rupturing groove is controlled with high precision. Therefore, the remaining thickness of the skin layer is measured after the airbag rupturing groove is formed. More concretely, since the airbag rupturing groove formed by the cutting blade is narrow in width as mentioned above, the remaining thickness is measured on the condition that the skin is bent and the airbag rupturing groove is opened (e.g., WO 2004/0045921A).